$ { \left[\begin{array}{rr}{1} & {-1} \\ {3} & {3}\end{array}\right]+\left[\begin{array}{rr}{1} & {1} \\ {-1} & {0}\end{array}\right] = {?} } $
Answer: To find the sum of two matrices, add the corresponding items between each matrix. ${\left[\begin{array}{rr}{1}+{1} & {-1}+{1} \\ {3}+{-1} & {3}+{0}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{2} & {0} \\ {2} & {3}\end{array}\right]}$